Update refuel.lua

I hope this works.

src/main/resources/assets/opencomputers/lua/component/generator/bin/refuel.lua

@@ -1 +1,38 @@
--- TODO Vexatos
+--[[ Makes the robot refuel itself using fuel from the inventory and lets you get the current fuel count.
+     Author: Vexatos]]
+local component = require("component")
+local shell = require("shell")
+
+local args = shell.parse(...)
+
+local function printUsage()
+print("Usages:")
+print("'refuel' to get the current fuel count")
+print("'refuel <slot>' to refuel from that specific slot")
+print("'refuel all' to refuel from all slots")
+end
+
+if component.isAvailable("generator") then
+  local g = component.generator
+  if args[1] = nil then
+    print("Current Number of items in generator: "..g.count())
+  elseif string.match(args[1],"%d") ~= nil then
+    print("Refuelling from slot"..args[1].."...")
+    local success, msg = g.insert(tonumber(args[1]))
+    if success then
+      print("Success.")
+    else
+      print("Error: "..msg)
+    end
+  elseif string.lower(args[1]) = "all" then
+    io.write("Refuelling from all slots...")
+    for i = 1, 16 do
+      g.insert(i)
+    end
+    print("Done.")
+  else
+  printUsage()
+  end
+else
+  print("This program requires the generator upgrade to be installed.")
+end